The use of electric motors is becoming increasingly popular in powertrain systems due, in large part, to their relatively high efficiency, responsiveness, and environmental cleanliness when compared with conventional powertrain systems that rely solely on internal combustion engine drive technology. In order to generate electric fields large enough to produce the relatively high output torque required of modern powertrain systems, these electric motors may be subjected to extremely high current levels. If not properly isolated and contained, current may be allowed to “leak” into other electrical circuits or systems, potentially decreasing motor and, ultimately, powertrain performance. If undetected, current leakage may cause serious damage to sensitive electronics and electric systems associated with a machine.
One common cause of a breach of electrical isolation, potentially leading to current leakage, may be a deterioration in insulation that surrounds the phase windings in the electric motor. Such deterioration may lead to breakdown in isolation between electric phases and/or between one or more phases and ground, potentially resulting in a short-circuit condition that may cause, for example, an arc-fault. Consequently, an accurate system and method for detecting deterioration in conductor insulation may be required.
Some systems and methods for determining the structural integrity of winding insulation in an electric powertrain may require the dismantling of the powertrain in order to test the resistance of the winding insulation. Such manual methods may increase maintenance costs and require significant machine downtime. Thus, accurately detecting insulation wear in an electric machine, while minimizing repair costs and machine downtime, may also be required.
One system for accurately determining the structural integrity of motor winding insulation, while reducing downtime and maintenance costs, is set forth in U.S. Pat. No. 4,766,387 (the '387 patent) issued to Browne et al. The '387 patent discloses a system for measuring the insulation resistance of a winding of a polyphase motor. The system includes a motor winding insulation resistance measuring circuit and a switching mechanism that allows for each motor winding to be coupled to a separate phase power source and the circuit. The insulation measuring circuit is then used to measure the resistance of a winding's insulation to ground while the motor is operating.
Because the '387 patent may provide a solution for determining a breach in the structural integrity of winding insulators during operation of the motor without requiring dismantling and manual inspection/testing of each insulator, it may limit machine downtime and maintenance costs associated with manual inspection techniques in certain situations. However, the complexity and customized nature of the system disclosed in the '387 patent, as well as the process of connecting the circuit to the motor, may make the system difficult to operate.
The disclosed system and method is directed to overcoming one or more of the shortcomings set forth above.